M&S says

Offering feminine style and unbeatable comfort in one pretty package, our cotton blend knickers come complete with elegant lace trims and a bow detail for a piece that you’ll love to wear. Beyond just looking stylish, these lace knickers are made from a sumptuously soft cotton blend that’s breathable to keep you feeling fresh.

* Buy 3 for the price of 2: Get 3 for 2 on selected women’s Knickers & Vests when purchased in one transaction at marksandspencer.com/en and in selected stores. Discount will be shown at checkout. Please check relevant delivery terms & conditions online. Eligible products must have the same delivery date and address for promotion to apply across all items. Offer does not apply to delivery charges. Subject to availability. Any refunds will take into account the discount.